Timing device



p 1961 R. A. COOLEY 2,999,910

TIMING DEVICE Filed May 26, 1955 Fjj I I I-INVENTOR.

R BERTA. C'ooLzv A TTORNE Y United States Patent Filed May 26,1953, Ser. N 0. 357,529 11 Claims. (Cl. 200-52) This invention relates to a timing device and more particularly to an electric time switch or fuse device suitable for controlling electric circuits such as circuits for governing the firing of the explosive blasting charge of mines or bombs of the type used, for example, to destroy either marine craft or land vehicles.

In the use of mines, bombs and similar blasting devices it is desirable that these devices remain inactive and that capability of actuation be delayed for a time during which installation operations are in progress or during which it is desired to allow unrestricted passage over the mine field for some reason. At the same time it is frequently desirable that the period when such devices are in armed condition and ready to go oil? be limited, after which either self-destruction or inoperability is desired. This may beaccomplished by means of a control device or actuator having a sequence of operation with suitable delay periods; and it is an object of this invention to provide a novel firing control device for interposing the desired delay and timing periods in sequence in the operation of blasting devices hereinafter referred to as mines. Another object is to provide a timing device occupying a minimum of space and having a minimum weight in order that the device be adaptable for functioning with a wide variety of contrivances. Another object is to provide a timing device of simple construction, small number and low in ertia of parts and free from complicated clockworks, yet efiicient and reliable in its operation. A further object is to provide an electric timing device of improved construction the calibration of which is not easily impaired and which is not adaptable to undesired actuation by enemy mine detection and clearing apparatus such as those of the magnetic, acoustic or electromagnetic induction type. A still further object is to provide a novel electric time fuse or electric switch device.

Other objects of the invention will be apparent from the following description and the accompanying drawing in which:

FIGURE 1 is a plan view, shown partially in cross section, of a device illustrating an embodiment of this invention.

FIGURE 2 is a cross sectional view of the device taken on line IIII of FIGURE 1.

FIGURE 3 is an elevational fragmentary view in cross section showing the device positioned in a marine type mine with a suitable ignition circuit depicted diagrammatically.

In accordance with this invention there is provided an electric control or switch device comprising an electric switch element carrying electroscopic member operable with predetermined timing by electrostatic forces controlled by variable charge leakage or ionization whereby one or more electric circuits may be closed with desired timing. Time control is obtained primarily by the intensity or magnitude of ionizing radiation flux such as emanations from radioactive material and also to some extent by the magnitude of the electrostatic charge impressed upon the carrier for the switch element. Briefly, the invention is an electroscopically actuated switching device.

It will be noted that the specific embodiment shown in FIGURES l and 2 of the drawing comprises in general a hollow radiation shield consisting of hollow fuse body 1 and a sealing cap 2 which together define an ionization 2,999,910 Patented Sept. 12, 1961 chamber 3 and house an electroscopic switch structure and the radioactive control elements. The fuse body 1 and cap 2 are formed of material comparatively impervious to radiation such as lead or preferably a plastic such as polystyrene containing particles of lead. Housed within the fuse body 1 are a rigid repulsion post 4 and an elongated flexible member 5 adjacent to but spaced from the repulsion post. The flexible member 5 carries an electric contactor 6 for connecting a first pair of electric circuit terminals 8 and 9 in chamber 3 and also carries another contactor 7 for connecting a second pair of terminals 10 and 11 also disposed in chamber 3. The sealing cap 2 rotatably mounted at one end of the hollow body 1, carries a movable support 12 for a pinhead source of radioactive material 13. A partition 14 of particular construction and either formed of radiation impervious lead or carrying a block of lead is positioned in fuse body 1 between the ionization chamber 3, containing an ionizable gas, and the radiation source 13. Extending outside the fuse body 1 are a first pair of insulated lead wires 15 and 16, connected to terminals 8 and 9 respectively, and a second pair of insulated lead wires 17 and 18, connected to terminals 10 and 11.

The fuse body 1 shown in the drawing is a hollow cylindrical or tubular structure. Mounted in one end of this body so as to protrude into the chamber 3 is a charge receiving plug 19 of electroconductive material such as copper and having a circumferential flange 20 for positioning the plug 19 firmly and accurately with respect to the fuse body. The plug 19 is insulated from the fuse body 1 by means of suitable dielectric material 21 such as sulfur, polystyrene, or polyethylene which also serves to seal the plug with respect to the body.

Mounted in electroconductive relationship in holes in the end of the plug in the chamber are the metal repulsion post 4 and the flexible member 5 which is preferably a quartz fiber sputter coated with a very thin layer of gold or platinum to render it electroconductive. Under electrostatic forces of repulsion between members 4 and 5, member 5 is adapted to be deflected curvilinearly from member 4 so that upon diminution of the repulsion force points on member 5 near the unsupported end return under elastic forces to a rest position opposite member 4 later than points near the supported end.

Electric terminals 8, 9, 10 and 11, also mounted in the body, consist of bare wires passing in spaced parallel relationship between the repulsion post 4 and flexible member 5 diametrically through the interior of the housing. The ends of the terminals are fixed in insulated relationship in the walls of the body 1 which may advantageously be formed by a molding process so as to include both the ends of the wire terminals and also the charge receiving plug 19. Although not shown, these terminals may be spaced from and supported at their midpoints by blocks of insulation attached to the repulsion post 4.

The end of the fuse body at which the charge receiving plug 19 is located is provided with an integral protrusion 22 having a central recess or bore for reception of a sealing plug 23 and also for reception of a compres' sion plug 24 disposed over plug 23 which is formed of some elastomeric material such as soft neoprene or rubber. As means for impressing a standard electric charge on the electroscopic elements of the device of this invention, there is provided a charging member or pin 25 preferably of stainless steel mounted centrally in sealing plug 23 and in frictional engagement therewith and having a sharp point 26 adapted to be forced into engagement with the charge receiving plug 19. The compression plug 24 is formed of the same radiation impervious composition as fuse body 1 and has a central perforation for passage of the pin 25 through the plug. When body 1 and plug 24 are of lead or any other conductive material, pin 25 is electrically insulated therefrom by any suitable clearance or other insulation so as not to impair the insulating relationship provided by insulating layer 21. The compression plug 24 has a male thread engaging with the internal threads of the bore of the protrusion 22 so that plug 24 may be driven down to put the sealing plug 23 under compression thus effectuating pressing of the point 26 of pin 25 into plug 19 and also closure of the central perforation of plug 23 when the pin 25 is withdrawn after electric charging is accomplished. To prevent undesired access to the plug 19 after assembly the compression plug 24 is secured in place by cement or adhesive between the threads, for example. The above described end-structure accomplishes a positive electric contact for charging purposes, a self-sealing charge communicating passageway for isolating the electroscopic elements from external electric disturbances, and an arrangement making it diflicult to impair the timing or to disarm the fuse device of this invention.

At the other end of fuse body 1, i.e. opposite the end in which the charge receiving plug 19 is mounted, there is provided a fixed partition 14, the structure of which will be described hereinafter, and a cap 2 formed of the same radiation impervious composition as the body 1 and constructed so as to provide a reasonably hermetic rotatable seal. The cap is shaped to have a circular cylindrical center section 27 which has a rather tight turning fit in an interior circumferentially enlarged bore section provided for the purpose in the end of fuse body 1. The outer end of the cap 2 consists of an exterior circumferential flange made up of a radially extending annular section terminating in a tubular section 28 coaxial with center section 27 and leaving an annular groove therebetween for telescopic reception of the annular tongue portion 29 of fuse body 1. To assure a sealing fit between body 1 and cap 2 a suitable sealing composition as paraflin, silicone grease or a low molecular weight polyethylene may be interposed between sections 27 and 29 and between sections 28 and 29 and as a further measure a suitable resilient sealing gasket 30 may be provided.

The center section 27 of cap 2 is provided with a threaded bore hole passing entirely through the cap which is also provided with a protrusion on the inner face thereof to form a safety detent 34 for holding the flexible electroscopic member in the outward position shown in FIGURE 1 and for preventing untimely closing of any of the switches of the firing circuits and the disastrous explosion that might follow. Disposed in the bore hole of cap 2 is an adjustable screw or carrier member 12 having male threads engaging with the threads of the bore hole so that the position of member 12 and the source 13 carried therein may be adjusted gradually with respect to the partition 14 and the ionization chamher 3 by means of a screw driver operating on slot 33 in the outer end of screw 12, for example. The position of source 13 may be indicated by index marks on the flat section 32 formed on the side of screw 12 to extend over part of the length of screw 12. The bore hole and its carrier screw 12 containing source 13, are positioned eccentrically with respect to the axis of rotation of cap 2; and safety detent 34 similarly is eccentrically positioned. This arrangement, as will hereinafter appear more clearly, permits movement of detent 34 away from the path of collapse of the contact bearing movable electroscopic member 5 while the radioactive source 13 is simultaneously moved away from behind a radiation shield of lead 37 and brought to act on the ionizable gas in chamber 3.

Cap 2 is secured on body 1 by means of a guide pin 35 mounted and carried on the annular tongue portion '29 of body 1. Pin 35 projects into slot 36 which is formed in and extends circumferentially part way around the tubular flange section 28 of the cap. The circumferential length of slot 36 is proportioned to allow the desired limited rotational movement (somewhat less than in the embodiment herein shown and described) of cap 2, carrier '12 and detent 34 all together as a single control unit. This arrangement also prevents any substantial longitudinal movement of cap 2 toward or away from the ionization chamber 3. Although only one guide pin 35 and slot 36 are shown in the drawing, it is to be understood that two or three such pins and a corresponding number of slots may be provided, if desired.

The inner end of the adjustable carrier member or screw 12 is formed with a perfectly fiat face square with the axis of rectilinear movement of the screw and is pro vided with a well 31 in which a pellet 13 of radioactive material is mounted. The flat square end face is designed to be closely abuttable against the flat surface of the block of radiation shield material 37 so as to definitely cut off emanation which might cause premature ionization. Moreover, center section 27 is also closely abutted against partition 14 to avoid the undesired transit of ions. A sealing material is applied to the threads of carrier screw 12.

The source of ionizing radiation is a small pellet or pinhead 13 of suitable radioactive material such as one of the radioactive isotope materials carbon 14, nickel 63, thallium 204, and sulphur 35. The longer lived radioactive materials such as carbon 14 are preferred in order to obtain a substantially constant source of radioactive emanations. Radioactive materials other than those enumerated may be used.

As shown in FIGURE 1, a partition 14 is located in the fuse body 1 between ionization chamber 3 and cap 2 which bears the radioactive source 13; but the details of the structure and function of the partition 14 with respect to the other parts can best be described in connection with FIGURE 2. This partition which is accurately secured in fixed position with respect to the fuse body 1 and the electrostatic elements 4 and 5, may consist of a suitable plastic material such as lucite or polystyrene having molded and positioned accurately therein a block of lead 37, a radiation window 38 and an arcuate slot 41 for reception of the safety detent 34. As an alternate construction, however, the partition 14 and the block 37 may be integral and consist of lead. In any event the radiation window 38 consists of several sections which extend in steps gradually from the slightly radiation pervious section 39, adjacent lead shield 37, to the substantially completely penetrable section 40, which may be a thin section of aluminum or plastic. The different sections of window 38 may consist of different materials or of different thicknesses in order that the window 38 be in effect an absorption Wedge for the radiation particles emitted by source 13. Diametrically opposite shield 37 and window 38 is an opening 41 through which safety detent 34 extends into ionization chamber 3. To accommodate movement of detent 34, the opening 41 should consist at least of an arcuate slot of adequate length.

Initially the position of detent 34 is as shown in FIG- URES l and 2 which may be referred to as the safe position. Here detent 34 projects to a point intermediate the unsupported ends of the electroscopic members 4 and 5 and prevents closure of any of the circuit terminals 8 and 9 or 10 and 11 by contactor members 6 or 7, respectively, carried by the coated movable electroscopic member 5 but insulated therefrom, or at least from the electroconductive coating thereon, by means of any suitable solid dielectric material such as fused quartz or glass designated as 42. It is to be noted that where only one contact is provided such dielectric material may be omitted. When the cap 2 with its carrier 12 and source 13 has been turned clockwise, looking at FIGURE 2, to position the radiation source 13 opposite section 39 or any other part of the radiation window 38, detent 34 has likewise been moved clockwise in slot 41 and operates no longer as an obstruction to collapse of any of the electric contacts upon their. respective switch terminals. When cap is turned as far as it will go from the safe position, source 13 is opposite section 40 of the window 38 where the least absorption occurs. Here the greatest ionizing effect is obtainable to give the shortest delay periods, provided carrier 12 is turned to place source 13 close to chamber 3.

To place the fuse device of this invention into operation it is necessary to first apply a standard electric charge, either positive or negative, of desired magnitude to charging pin 25 which is thereafter pulled out so as to allow sealing plug 23 to close upon its central perforation thus electrically isolating the electrostatic charge impressed on plug 19," post 4 and electroscopic movable member 5. This charge is responsible for an electrostatic force of repulsion between the rigid repulsion post 4 and member 5 which is flexible and hence bends away from post 4 as illustrated best in FIGURE 1. Next the threaded post or carrier member 12 is adjusted as indicated by the index figures thereon to place source 13 at the desired proximity with respect to the ionization chamber 3. Just before but not until the device of this invention is ready for immediate use, cap 2 is turned to move the safety detent 34 from the position between the repulsion post 4 and flexible member 5 shown in FIGURE 1 and FIGURE 2. This arms the fuse device as will be indicated by departure of an indicia such as an arrow on cap 2 (FIGURE 1) from an indicia designated as SAFE on body 1. Turning of cap 2 is continued until the source 13 is brought opposite the desired absorption section of radiation window 38 as indicated by other suitable index figures which are imprinted on the exterior surface of fuse body 1 adjacent the surface of cap 2 bearing the arrow indexing reference point. In this manner the fuse is put into operation at the desired timing period.

With the source of ionizing radiation adjusted suitably and the safety detent out of the way, the flexible electroscopic member 5 is free to begin collapse toward charged repulsion post 4 because of the restoring force of the elastic member 5 carrying contactors 6 and 7 toward their respective switch terminals. It will be noted that the speed of collapse is determined by the initial electric charge on the electroscopic elements 4 and 5, by the type and amount of radioactive source material 13, by the proximity of the source 13 with respect to the ionization chamber 3 and by the interposed section of the radiation window 38. The drop in electrostatic repulsion force between repulsion post 4 and electroscopic member 5 and hence the time of approach of the electric contact 6 toward its terminals 8 and 9 and the time of approach of contact 7 toward terminals 10 and 11 is primarily controlled by varying the strength of the radiation emanating from the source 13 and etfecting ionization of the gas in chamber 3. But it will be understood that the period of collapse of the electroscopic member 5 may be controlled further by variation in the electric potential applied to pin 25. As the gas in the ionization chamber 3 becomes ionized by radiation entering the chamber, ions are attracted to the charged electroscopic members 4 and 5 and tends to neutralize the charge which as a result leaks off the electroscopic members allowing the movable electroscopic contact carrying member 5 to return in due course to the position shown in dashed lines in FIGURE 1 and designated as 5 where contact 6 bridges terminals 8 and 9 and where contact 7 bridges terminals 10 and 11. It is evident that diminution of the electrostatic force of repulsion results in closure of terminals 8 and 9 first by collapse thereon of contact 6 which is followed after a time by closure of terminals 10 and 11 by contact 7. The current carrying capacity of the switch elements is of the order of about It] millia-mperes.

The period from withdrawal of safety detent 34 to closure of contact 6 on terminals 8 and 9 may be from a few minutes to as long as an hour. The active period from first closure of contact 6 to closure of contact 7 on terminals 10 and 11 may be from a few seconds to several hours. These time intervals will be determined at their extremes by the distances at which the contactors and terminals are positioned in the device of this invention and also by the dimensions, particularly the amount of taper of the flexible member 5. Maximum time intervals are obtainable when the ionizing influence on the gas in the chamber 3 is the least.

There now follows a description of the operation of the device of this invention in a military mine with reference to FIGURE 3 of the drawing. The mine shown in the figure consists in general of a metal casing 43 containing an explosive blasting charge 44 of trinitrotoluene, tetryl, cyclonite or the like. The casing 43 is shown provided with an opening 45 and a closure 46 therefor. The casing 43 and closure 46 are shown provided with externally protruding instrumentalities such as 58 and 59 any one of which is adapted to detect and be actuated by a passing vessel thereby closing a firing switch such as switch 51 and causing explosion of the mine and destruction of the vessel.

In the firing mechanism of the mine the electroscopic fuse of this invention is designated as 60 and is shown, diagramatically, mounted in the mine upon the frame 61 which is part of the closure 46 which is sealed with respect to casing 43 in any suitable way as by brazing metal 47. The firing mechanism consists of an electric detonator 49, a battery 50, one or more firing switches 51, the electroscopic fuse device 60 and a resistor 52. The blasting charge 44 has a well 48 in the upper face thereof for reception of the electric detonator 49 the initiability of which is to be controlled by the electroscopic fuse and associated firing mechanism. One terminal of detonator 49 is connected by wire 55 to one end of the battery 50 while the other terminal of the detonator 49 is connected through lead wire 16 to one switch terminal 9 (identical with terminal 9 in FIGURE 1) in the hereinbefore described electroscopic timing device. The other terminal 8 of this switch is connected through lead 15 to firing switch 51, which in turn is connected through wire 56 to the other end of the battery 50. Thus the battery 50, the detonator 49, the terminals 8 and 9 in electroscopic switch device 60 and the firing switch 51 are connected in series to form a main control circuit the function of which is to permit actuation of the mine only during a desired time interval which however does not begin until after a desired delay period has passed. Termination of the interval during which the mine is capable of being set off by way of contact with or actuation of any suitable instrumentality such as 58 or 59 operating a switch such as 51 (or a similar switch in parallel with switch 51) is obtained with an auxiliary circuit in parallel with battery 50. This circuit includes a battery discharge resistor 52 connected to one end of the battery by wire 57 and to terminal 10 of the other switch in fuse device 60 by lead wire 17 attached to resistor 52 at connection 53. The other terminal 11 is connected by lead wire 18 to the other end of the battery 50. It is to be noted that the resistor 52 and the second pair of switch terminals 10 and 11 located in the hereinbefore described electroscopic timing device are in series in the auxilliary circuit. Until terminals 8 and 9 are bridged by their contactor, inadvertent contact with protruberances 58 and 59 during handling in transit and mine laying will not fire the mine although the electroscopic fuse device has been previously charged, set into operation and even closed up in the mine at some distribution point, for example. After a predetermined time interval such as half an hour, for example, sufficient for completion of the mine laying operation and evacuation of the mined area by the mine layers, the main control circuit is completed when terminals 8 and 9 in the electroscopic blastic actuator of this invention are bridged by contactor 6 as described hereinbefore in con nection with FIGURES 1 and 2; and for a predetermined period thereafter the mine is capable of being set ofi with destructive affect on the enemy. Upon eventual bridging of terminals and 11 in the electroscopic device of this invention, the auxilliary circuit is completed to permit the battery 50 to exhaust itself through resistor 52 thus rendering the mine inoperative. If self-destructon of the mine is desired lead wire 17 is attached to connection point 54 on lead instead of being connected at 53 to the resistor 52.

According to another aspect of this invention the electroscopic switch may comprise a hermetically sealed housing enveloping an ionizable gas under subatmospheric pressure. It is also to be noted that while the device of this invention has been described as having two switches it may include only one switch or three or more such switches. Likewise, it is evident that whereas the electroscopic members are described as consisting of one immovable repulsion post and one repellable contact carrying member, the electroscopic members may be a pair of mutually repellable members each carrying one or more contacts or may consist of an immovable repulsion post having arrayed about it two or more repellable contact bearing members with terminals or electrodes disposed between said electroscopic members for coaction with contacts on the repellable members. Furthermore, although the device has been described in connection with a battery, it will be understood that it may be used with other voltage generators and also with various devices and instruments particularly those of the electronic type. Although a military fuse is shown and described as one specific embodiment of the invention, it will also be recognized by those skilled in the art that other embodiments may be devised having utility for commercial non-military uses.

Since many other embodiments of this invention may occur to those skilled in the art, it is to be understood that the foregoing is intended by way of illustration of a preferred embodiment and not as a limitation of the scope of the present invention except as set forth in the appended claims.

What is claimed is:

-l. A timing device for controlling the closing of electric circuits with predetermined delay comprising a substantially hermetically sealed housing of substantially radiation impervious material, an ionization chamber in the housing containing an ionizable gas, an electrostatic charge receiving means mounted on the housing and extending into the chamber, an immovable electrostatically chargeable electroscopic member mounted at one end in the charge receiving means, a flexible electrostatically chargeable electroscopic member also mounted at one end of said member in the charge receiving means in spaced apart relationship adjacent said immovable member in electro-conductive relationship with said immovable member, a first pair of circuit terminals disposed between said electroscopic members adjacent their ends mounted in the charge receiving means, a second pair of circuit terminals also disposed between theelectroscopic members and displaced from said first pair in the direction toward the unsupported end of the electroscopic members, a first electrical contact means carried on said flexible electroscopic member adjacent the end thereof mounted in the charge receiving means and electrically insulated from said electroscopic member for closing said first pair of circuit terminals, a second electrical contact means displaced from the first contact means and carried by said flexible electroscopic member in electrically insulated relationship therewith for closing said second pair of circuit terminals, means for impressing an electric charge on said charge receiving means from a point outside the housing to cause the flexible electroscopic member to be repelled from the immovable member whereby both the first and second contact means are removed from the first and second pair of circuit terminals respectively, means for subjecting the gas in the ionization chamber to ionizing radiation with an intensity causing the first contact means borne by said flexible member to collapse upon and bridge the first pair of circuit terminals at a predetermined, time after impression of the electric charge and thereafter causing the second contact means to collapse upon and bridge the second pair of circuit terminals at a predetermined time after closure of the first pair of terminals.

2. A timing device for controlling the closing of electric circuits in sequence with predetermined timing comprising a pair of electroscopic members mounted in electroconductive relationship in a confined atmosphere of ionizable gas, an electro-conductive charge receiving means, a plurality of pairs of circuit terminals, electrical contact means for each of said pairs of terminals for closing the circuit of the corresponding terminal pair, and means for subjecting the ionizable gas to ionizing emanations, said electroscopic members consisting of an electrostatically chargeable immovable rigid repulsion member one end of which is mounted in the charge receiving means, and also mounted in said charge receiving means in spaced apart relationship with and adjacent said immovable repulsion member an electrostatically chargeable movable member yieldably urged into close proximity with said immovable member and adapted to be repelled from said immovable member when both members are electrostatically charged, said pairs of circuit terminals being positioned between said immovable and movable members, said contact means being carried on and disposed along the length of said movable member in juxtaposition with respect to said terminals, insulated from said contact carrying member, said plurality of pairs of terminals being disposed between said movable and repulsion members in a linear array such that the first pair of terminals is disposed nearest the fixed ends of said members while the last pair is disposed nearest the free ends, and means for electrically charging said charge receiving means and both electroscopic members whereby the movable contact carrying electroscopic member is repelled from said repulsion member thereby withdrawing all said contact means arrayed thereon from said circuit terminals to open circuit position, said ionizing means consisting of a radioactive source of predetermined strength the flux intensity of the emanations of which are adjustable whereby the interval of time required for return of said movable electroscopic member into close proximity with the immovable repulsion memher and for the resulting closure of the circuit terminals in sequence is controlled.

3. An electroscopic timing switch device comprising an electrostatically chargeable elongated repulsion member, an electrostatically chargeable elongated repellable member, open circuit switch terminals disposed between the repulsion member and the repellable member, and a circuit closing and opening switch contactor electrically insulated from and carried by said repellable member in such position that the switch contactor is moved to open circuit position when the members are fully electrostatically charged with a charge of identical polarity and such that the switch contactor is movable to the closed circuit position after the passage of an interval of time at the end of which the repellable member has collapsed toward the repulsion member sufficiently as the charge upon said members leaks away to permit said switch contactor to bridge said open circuit terminals.

4. The electroscopic timing switch device of claim 3, provided with means for varying the leakage from the electroscopic members whereby the interval of time required for closure of the circuit terminals is controlled.

5. The electroscopic timing switch device of claim 3, provided with radioactive means the emanations of which are adapted to control the interval of time required for closure of the circuit terminals.

6. A timing device comprising electrodes, electrostatically chargeable repellable members, charging means, and means for electrically connecting said electrodes upon movement of one of said members resulting from diminution of the charge.

7. A timing device comprising electrodes, electrode carrying electrostatically chargeable members, said electrodes being normally under spring contact but adapted to move out of contact against the spring contact tension with said members upon each member receiving acharge of identical polarity, and ionization means to neutralize the charges on the members and thus permit contact between said electrodes.

8. An electroscopic timing device for controlling the closing of an electric circuit with predetermined timing comprising a housing of substantially radiation impervious material having a chamber therein for confining an ionizable gas, a pair of spaced electric circuit terminals positioned in said housing, circuit lead wires connected to said terminals and passing out of said housing, a contact member in said housing adapted to bridge said terminals for closing said circuit, means for supporting said contact member in juxtaposition with respect to said terminals comprising a deflectable electrostatically chargeable elongated member, an immovable electrostatically chargeable rigid elongated repulsion member mounted adjacent said contact supporting means for exerting an electrostatic force of repulsion on said deflectable member, electroconductive electric charge receiving means on said housing for supporting said repulsion post and contact carrying member within the housing in electroconductive spaced relationship, removable electroconductive charging means contiguous with said charge receiving means and accessible from the exterior of the housing for impressing a measured electric charge on said charge receiving means whereby the contact carrying member is repelled from said repulsion member to carry the contact member away from the circuit terminals, means for closing olf said charge receiving means from the exterior of said housing upon removal of said charging means, means for controlling the rate of return of said deflectable electroscopic contact supporting member by effecting ionization of said gas in the chamber, and comprising a source of radioactive material emitting ionizing emanations, means for adjusting the proximity of said source with respect to said chamber, means interposable between said chamber and source and having areas each penetrable to a different extent by said emanations, shield means interposable between said chamber and source to prevent any emanations from said source from penetrating into said chamber, detent means interposable between said repulsion member and contact supporting member for preventing the contact supporting member from returning toward said repulsion member and allowing the contact member to inadvertently bridge said terminals in the absence of a repulsion charge adequate to prevent such return, and means for removing said detent from a position between the repulsion member and contact supporting member while simultaneously removing the shield means from a position intermediate the source and ionization chamber and for thereafter interposing between said source and chamber one of said areas penetrable to a desired degree by the ionizing emanations from said source whereby the electrostatic charge on said repulsion member and contact supporting member is caused to leak of!" at a desired rate to allow the contact member to bridge said terminals after a predetermined interval of time has elapsed from impression of the electrostatic charge.

9. An electroscopic timing device for controlling the closing of a plurality of electric circuits in sequence with predetermined timing comprising a housing of substantially radiation impervious material having a chamber therein for confining an ionizable gas, a plurality of pairs of spaced electric circuit terminals positioned in said housing, circuit lead wires connected to said terminals and passing out of said housing, a plurality of contact members in said housing corresponding in number to the number of pairs of terminals and adapted to bridge said terminals for closing said circuits, means for supporting said contact members in juxtaposition with respect to said terminals comprising a deflectable electrostatically chargeable elongated member, one end of which is fixed against movement and the other end of which is free to move, an immovable electrostatically chargeable rigid elongated repulsion member mounted adjacent said contact supporting means for exerting an electrostatic force of repulsion on said defiectable member, electroconductive electric charge receiving means on said housing for supporting said repulsion post and contact carrying member within the housing in electroconductive spaced relationship, said plurality of pairs of terminals being disposed between said dellectable and repulsion members in a linear array such that the first pair of terminals is disposed nearest the fixed end of said defiectable member while the last pair is disposed nearest the free end, removable electroconductive charging means contiguous with said charge receiving means and accessible from the exterior of the housing for impressing a measured electric charge on said charge receiving means whereby the contact carrying member is repelled from said repulsion member to carry all the contact members arrayed thereon in correspondence with said array of terminals away from the terminals to an open circuit position, means for closing olf said charge receiving means from the exterior of said housing upon removal of said charging means, means for controlling the rate of return of said deflectable electroscopic contact supporting member by efiecting ionization of said gas in the chamber and comprising a source of radioactive material emitting ionizing emanations whereby the contact members are carried in sequence to a closed circuit position, means for adjusting the proximity of said source with respect to said chamber, means interposable between said chamber and source and having areas each penetrable to a different extent by said emanations, shield means interposable between said chamber and source to prevent any emanations from said source from penetrating into said chamber, detent means interposable between said repulsion member and contact supporting member for preventing the contact supporting member from returning toward said repulsion member and allowing the contact members to inadvertently bridge said terminals in the absence of a repulsion charge adequate to prevent such return, and means for removing said detent from a position between the repulsion member and contact supporting member while simultaneously removing the shield means from a position intermediate the source and ionization chamber and for thereafter interposing between said source and chamber one of said areas penetrable to a desired degree by the ionizing emanations from said source whereby the electrostatic charge on said repulsion member and contact supporting member is caused to leak oil? at a desired rate to allow the contact members to bridge said terminals pair by pair in sequence with predetermined time delays.

10. An electrical timing device comprising circuit controlling electrodes, electrostatically chargeable relatively movable members, means for electrostatically charging said members, and circuit controlling means carried by at least one of said movable members and movable therewith for electrically connecting said electrodes after passageway of a predetermined interval of time upon relative movement of said members resulting from leakage of said charge at a predetermined rate.

11. The electroscopic device of claim 1 wherein the housing includes lead.

References Cited in the file of this patent UNITED STATES PATENTS 1,605,911 Banneitz Nov. 9, 1926 

